Automatic distributing system.



L. D. KELLOGG.

AUTOMATIC) DISTRIBUTING- SYSTEM. APPLICATION FILED JUNE 15. 1907.

960,176. Patented May 31; 1910.

2 SHEETS-SHEET 1.

ZT/IQE GRoupl I I L Gr w 3 v 4 m L. D. KELLOGG.

AUTOMATIC DISTRIBUTING SYSTEM.

APTLIOATION FILED JUNE15, 1907.

Patented May 31, 1910.

. citizen of the United States, and resident o To all whom it concern:

UNITED PATENT onrion.

LEROY n. KELLOGG, or outdated, fi ILINOIS, 'ASSIGNOR, BY MESNE ASSIGNMENTS! r KELLOGGI swI'rcHBoAm) .&' COMPANY, A CORPORATION or ILLINOIS.

AUroMArie fliTE-TBUTING SYSTEM.

Be it known thatI. Lanov D. KnLLooG, a

Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Automatic Distributing Systems, of which the following is a specirequired fication.

My invention relates to telephone Systems wherein selective switches are employed to automatically distribute the incoming calls among .the operators, concentrating the business before as many operators as are to attend to the total business at; a

ivenperiod of theday, and has for. its obect', the provision of means for producing certain economies in the operation of such system and a more complete concentration of calls.

hIn accordance with my invention, I pro= vide a considerable number of. cords, say, n1nety-five in a group, .1n associat on with which isa selectiveswitch to cause interchangeable connection'of the cords with calling lines. Such a switch selectively picks out the particular cord tobe used for any connection and is a. restoring switch such that at'its position of rest it has a definite *serial relation to the cords of a-group. 'I

provide the cords \Vliltlillllllltll contacts at the switch arran 'ed lnre ular order so that rest, itvtests the cords successive y, making first a test of the cords to one opcrators position, and'thereafteratest. of the cords to a second operators position, and so on. If there is a contact-of an idle cord of the first position, the selective switch will be sensitive to the electrical condition of that con-Q --tact and will cause that; cord to be used for the impending connection, and so for the other position. 1

The selective switch is started responsive to a call initiated over a subscribers line and thus tests thecords for the purpose ofcaus: ing the line to beconnected to a'cord at the first" idle operators position. .Assume a group of lines capable, on initiation of calls,

of causing the same cords to be tested after the manner described, and it will be 'ap arent that the calls of the line-group W11 "be condensed at a first 'operatorisl position until osition of ters- Pfitent.

I said line-group coming in will go to a next operators position, as long as all cards of the first are busy. For each call, a separate test ofa'li cords seriallv from 'tho first up to an idle cord is made: so that as soon asa cor-d becomes idle at the firstposition, the next initiated cal-l will be lodged thereat.

- Suppose each operator hasten cords; then when twelve co-existing calls from a linegroup are present, one position will have ten cords used, and the next position but two.

i If a thirteenth call comes-in at-once, the secondposition will have three calls; but if,

porarily stop coining, to the secondposition; and with the fluctuations of the call load, the second operator wilhfor a time at least, have a small and irregular quantity of busimess to attend to, until a quite perceptible and steady increase in the number of calls from the line-group takes place. Similarly. ifjthe load increases so that two operators are busy, on a further slightincrease of business. a small amount of business will for a time irregularly go to a third position, and

so on. l

In carrying out my invention, I contemplate the employment of a number of groups of cords, each comprising, for example, ninety-five cords. Such anumber of cords thousand subscribers; and for a ten thousand subscriber exchange, there would be ten groups of ninety-five cords each, each group being tested responsive to. calls iniwould thus beatmost times several of what them to their full capacity, it will be seen there would be an element 0 considerable waste off-operators time and consequent wages. It is to the taking care of this waste thatmy invention is particularly directed.

I'accomplish it, briefly stated, by providing tiated over .one thousand lines. Theremay be called the ragged positions; and as at once that in the several ragged positions Patented May 31. 1910.

= all cords are busy, whereafter additional "soon after, the first operator has two or three cordsbecome ldle, additional calls will i em ,may be assigned to-a group 0t, say, one

had; but instead of being distributed among a maximum of ten slightly employed operators, it will be condensed at two or three operators positions where the operators will be fairly busy, although fiuctuatingly so.

Thus in my invention, I add to the features of condensing calls before operators, the feature of condensing what would otherwise be ragged position calls. which I claim as my invention.

I have illustrated schematically in Figure 1 a specific embodiment of my invention, in which the mechanism to be employed may be that illustrated in Fig. 2, which shows circuits and mechanism of a specific cord testing telephone exchange system. In Fig. 3 is shown the circuit of a common lamp that may be employed in connection with the circuit of Fig. 2. I

The preceding general description explains the scope of the invention claimed, while the following description of the figures will exhibit concretely a single specific embodiment thereof, it being understood that my invention has reference to the arrangement of operators link-circuits with or without manually operated terminals, their testing, and the resultin distribution of calls, and not to any speci 0 means forconnecting the link-circuit to the calling line, although the calling line must becapable of influencing a testing switch. The invention is, in its general aspects, applicable to structures employing individual test switches for lines or a common test switch for lines.

In Fig. 2, I show the lines of two subscribers A and B with their respective individual test means C and D, which not only serveto determine which operators .circuit is to be used, but also include the connecting means for placing the line in connection with the link-circuit. This testing and connecting means takes the form of a selective switch individual to a calling line, and that of each line would be the same as that of line A, as shown at C, comprising the traveling connecting or line wipers 27 and 2S and the test or private wiper 29. These wipers are mounted on a rotary shaft 35 carrying also'a ratchet 34-, which, when actuated by the pawl 36 of magnet 33, is turned, carrying the shaft and wipers with it, thelatter sweeping over their respective multiple contacts 30, 31, 32. Each set of contacts 30, 31,

32, other than the normal set, engaging which the wipers are shown, is connected by conductors 3 8, 39, -40, to the circuits of a pluigu terminal, 62, 63, one'only being shown in ll. At C, I have shown for simplicity is to be understood that in practice a' greater but seven sets of terminals-30, 31, 32 but it number could be provided and-in explainmg my invention, each switch such as C or I D will be assumed to comprise ninety-five sets of contacts30, 31, 32, each set being connected to adifferentoperators circuit. At 30 31, 32, I have shown one set .of multiples of the contacts 30,31, 32, which ,mul-

tiples are includedin the switch E, assumed to belong to the line of'another subscriber.

As ninety-five o erators circuits would provide suflicient acihtles for one thousand lines, the contacts 30, 31, 32, would in prac ticelbe multiplied one thousand times, onceto the switch of each subscriber .in a thou-' sand group. A second thousand group of subscribers would have multipled .to their one thousand switches a second group 'of contacts 30, 31, 32, of ninety-five o erators circuits, and so on for the other t ousand subscribers groups. The wipers of the switch C of the line of A are shown in their normal position, to which they are returned after each use of the switch. When traveling, their motion is clockwise, or from left to right, and at each step they move from one set of contacts to the next. I

. Briefly, the operation of the system of Fig.

2 is asfollows: ThecallingsubscriberA rethe called line, it being understood that' each line has a multiple jack within reach of every operator, in the usual way.

In Fig. 1, showing schematically the novel arrangement of connections, the contacts of each cord are represented by its private contact 32 only, and these are shown for simplicity as spread out in a straight line, instead of circularly disposed as shown in Fig. 2.

At 1 are shown the ten plug terminals for operator 1 of line-group 1, connected to the first ten sets of private multiples 32, 32. At 2 are shown the plugs for the second operator connected to the second groupv of contacts 32, and so on up to operator 9, operators positions 46 being interposed at the broken space.

' plugs at the overflow board.' Similarly, the

first tencontacts 32 of line-group 2.are connected to plugs at the first operators too position 1 for the group; the next ten to plugs at position 2*; and so on to position W; wliereafter the five contactsO' lead to the overflow board. Similarly, the first ten contacts of line-group 3 lead to the firstoperator's position 1 for lin-group-S; the next. ten to position 2 and so on for nine positions. wh'ereafter five contacts are connected to plugs at the overflow board.

I Assuming 5 that the foregoing is con-v tinued for ten subscribers groups,- eacl 'including one thousand subscriber; lines, and having each ninety-five cords, there would be nine hundred cords at the regular positions and fifty cords at the" overflow board.

In the structure of F ig.]2, a subscriber's ally operated gang switch which may coniprise the pivoted switch-arms 6."), one iii-. serted inthe circuit of each contact and provided with a bar (it; for shitting the arms 63 simultaneously to connection with their respective grounded contacts 66, or to connection. with the'link-circuit conductors e0. An individually operable switch-arm 67 is also provided in the circuit of each contact 32 for connecting the contacts to the ground connections 67, orto the-conductors 40. The manually operatcdswitches are preferably provided at a monitor's desk and she is enabled by the bars 66, one of which is to be provided for each operators position, to render the link-circuits of a position artificially busy or idle. .I have shown the gang switches and the individual switches for the link-circuits of positions 1 and 2 of line-group 1 only, those of position 2 being. shown'as rendering the link-circuits busy, while those of position 1 are in the positions rendering the circuits selectable, but it will be understood that corresponding switches are to be provided for the link-circuits of all positions of all line-groups.v

In the idle hours of the day, the cords of all operators positions of each line group may have their manual switches shifted to the busy position, exceptlthe' cords of the first position "of each linegroup. The overflow cords O, 0', 0 etc., may be al -ays left selectable. The first ten simultaneous connectionspf the'line-groups' will then go to the first positions of the respective groups; and" as soon as more than ten calls COGXISC from a group, the last ones will pass over the contacts of ailintervening positions till they reach the overflow cords 0, one of which will beselected.

and its signal displayed at the overflow board. I provide a common signal lam preferably located at the monitors' 'des operated when the five overflow cords'ofa' line-group are all displayed. so that the monitor will then know that there is enough'business from a line-group to keep an additional operator at least one. half busy. The monitor may then if She desires, by her manual switches. cut in one or two cords of the position of operator 2, whose calls operator'l may take care of. will temporar ly relieve the overflow positionz and as soon as the common lamp is a second time displayed, the ope 'ator will,

This

all? overflow or ragged position calls of the ten groups. Of course, when an additional operator has Just been assigned to a linegroup. there will for a time be no calls from that group reaching the overflow board. The cords there will thus rarely, if ever, be all in use and three or four operators at the overflow board would be sufficient to handle such overflow business.

It remains to describe in detail the specific system shown iii-Fig. :2. The calling subscriber at A, removing his receiver, causes the switch-hook to assume its alternate position. whereoii current flows from "-batterv-ii', line relay 13, contact 15, limb 12.

through transmitter and receiver, alternate switch-hook contact, returning over limb 11, contact 16 to ground. Relay l3 attracts its armature, establishing a circuit from ground at off-normal contact ()X, armature of relay 13; contact 24, relay 1? to battery, which. relay 1?, by attracting armature. 1S). coi'mects laittcry fru'm contact 15 through .altcrna-te contact 19, to the sleeve contacts :20 of-the line jacks. rendering them busy.- By attracting armature 20, relay-1T completes a circuit. including alternating current generator 3t" and magnet 33; and successive impulses will be transmitted through magnet 33, causing the energizatit'm and decnergization thereof as long as relay 1? remains operated and Contact 20 hence closed. Each actuation of magnet 33 effects a. thrust of pawl 36, tllll'llll ratchet .bl, shaft -35 and wipers 27, 28 and 29a step, the wipers thus engaging terminal contacts 80, 31 and 32 of successive link-circuits terminating in plugs comprising contacts 62, (i3. \Vith the first step oftheswitch, the stud of insulation on-ratchetii ijdisengages the coinple mentary, stud on elf-normal spring ON,

whereon the spring, by its tension, leaves its normal contact and engages its alternate contact, thus opening the initial energizing 5 circuit of relay 17 The said relay has, howeveryrby' thea'ttraction of armature 21, completed a circuit extending from battery, through relay 17 contact .23, alternate contact -21Lto test wiper'29; and as the test Wiper '10 is sufliciently broad to engage a next contact '32 before leaving the one previously engaged by it, relay 17 will be held operated untilthe "wiper 29- has reached an ungrouuded contact 32 which will pertain, of course, to

an idle link-circuit, at which time line wipers 27 28, will be engaging the talking 7 contacts 30, 31, of the idle link-circuit. This is assumed to be the link-circuit shown'in fullill'Fig. 2. Relay 17, havin its circuitnow openedat contact 2932, ecomes de-- any other selective switchengaging a mul l tiple of contact 32 will find a locking circuit for its relay 17 extending to ground through.

a multiple engaged by wiper. 29 of 'SWitCh'C at the alternate ofi-normal contact 'ON- of said switch C. Such circuitwill be of sufficiently high resistance not to permit the acv35 tuation of the relay 64 of the switch 0, 511- though enough current will flow to prevent the relay '1'? of the other switch from re-.

leasing its already attracted armatures.- Armatures 18, 1.9, and 20 of relay 17 of 40 switch C were also retracted on itsdeenen gization, whereupon a circuit is completed as follows: from battery 37, through relay 44, over conductor 39, contact til-28, normal contact 19,-cut-o1i relay 14 toground through normal, contact 20. This operates relays- 44and 14, whereon the latter operatively disconnects the line relay 13 by attrac'ting its armatures 15 and 16. Armature '19 of relay 17 also connected battery 37 with the sleeve contacts v26 of the line jacks so that they continue busy. Circuit is also at this time closed through relay 41 extending from ground over conductor 38,. contact 3027, normal contact 18, over the line limbs, returning'to battery through alternate contactlG and relay 44. Attracte'd armature 43 of relay 41 completes a circuit extendin 0 from ground at normal contact -51 and through call-signal lamp 4? to battery, caus ing its display whereupon the operator throws over levers 57 and 58 ofher listeningkey and ascertains the number of the called .su'bscribers line from the calling subscriber A, thetalking circuit of the calling substation being indicated by the heavily marked conductors. The operator now touches tip contact 62. of her calling plug to sleeve contact 26 of the called line-that. of B. If this pertains to a busy line, the said contact 26 will be at a potential other than ground and current will flow through contact 62, normal contact 60, normal contact 53, alternate contact 51?, high wound test relay 56 to ,ground, thetest relay then attracting its armature to close the circuit of'the tertiary winding of the operators induction coil, whereupon she ill hear the usual busy click and know that the called line is busy. The callingsubscriber, being Q then advised of this fact by the operator,

will replace his receiver, which will be effectivecto deenergize the relay 41 whose circuit included the limbs of the line. Circuit will thereupon be completed as follows:

from battery 37, through lamp 47, normal contact 42, normalcontact 50,-attracted armature 44, over'conductor 40, contact 32-2), normal contact 21, relay 64 to ground at the shifted oft-normal contact ON. The resistits alternateto its normal contact,f'and the iwitch proceeds to thus" travel, the circuit or its magnet 33 bein closed through at tracted armature 20 of relay 17. It will be-seen that while the switch is traveling,

relayi7 is always operated; and by its attracted armatures 18 and 19, maintains wipers 27 and 28 on open circuit, preventing interference. with existing conversations as Assuming that the called line was idle rather than busy, the operator inserts the they'yvipe over contactsof busy link-circuits.

plug into the springjack of the-called line, v asuined to be B, closing contacts 6326 and 62-25, current then flowing from battery 37',

through relay 49, contact (5326, cut-ofi' relay 14, to ground through contact 20 of the called line circuit, operating the cut-ofi relay 14, which disconnects the line relay 13 from line'limbs11-12 and connects the said line limbs through the alternate contacts of armatures 15 and 1G with contacts 25, 26, of the line jacks. The-operator now throws over levers 60 and (31 to include generator .59

station, ringing the'bell, returning over .125 tact 62-25, alternate contact15, line limb 12, through condenser'and bell of the suboperated. .were not relay seams limb 11, alternate, contact 16', contact 243-63, f

contact 61 to ground. The operator then releases levers 60 and 61 and the calling supervisory signal 55 will remain displayed until theca'llcd subscriber answers the call, its circuit being traced from ground at the back -contact of the armature of relay as, alternate contact, 52, to battery 37. The relay 49 was operated on the insertion of the plug into the springjack,to attract its arms.- t-u'res whercon completed a normally open contact in the tip strand of the cord, and 51 completed a break in the circuit of answer: ing supervisory signal 54, which would be 41 at this time energized. By the attraction of armature 50, the control of the releasing circuit, before described, is removed from the calling subscriber and an additional and lowre sistance ground placed from alternate contact via' alternate contact 4% upon the multiple contact i When the called subscriber answers the call, theremoval of his receiver, causing the elevation of the switch-hook, completes a circuit for relay 48 extending therethrough from ground, alternate contact 53, contacts 60, 62-25, over the line limbs, returning;

through contact 2663 to battery, through relay 19. The two subscribers A and B are now in conversation, the talking circuit being traced from substation to substation through the exchange by the heavily marked conductors, the encrgization of relay l8 having opened the circuit of calling supervisory signal 55, rendering it inert, to notify the operator that the call is answered.

l/V'hen the subscribers finish conversation, they replace their receivers, whicl-r acts will cause the dcncrgizations of relays i1 and 48 and the consequent displaypof the two supervisory signals 54 and 55, the dcenergization of relay ll failing, however, to

1 release switch C because alternate contact-'50 will remain open until the operator withdraws the calling plum In response to the display of the signals, the operatornow removes said plug, hereon relays 49 and 14 are deenergized, the denergization of.

the former causing the retraction of its arlnatures,.whereon 52 and 51 open the circuits of signals and 5 1 which becomev inert, wlnle the retractlon of armature 5O closes the before-described release circuit extending from battery 37, through call lamp 4:7, normal contact 42, normal contact 50, attracted armature 44 conductor 40, contact 32-29, normal contact 21, release relay 64 toground through'alternate contact )N. The switch C. theretorefis restored to normal as before described, circuit through rel'ay' l'-l and lamp 47' being opened as soon as the switch wipers leave the cor tacts .30, all, of cc repl the-switch C is operating under the influence of its release relay 6%.. In case of an accidental ground upon limb 12, relay 13 would be continuously held energized; and after the switch'started to operate with relay 6% energized, a continuous operation would be produced because the restoring circuit, 1neluding relays 17, 64', has a branch extending through the armature of relay 13 to ground at spring ON, which spring, in shifting from its normal to its alternate contact. or vice-versafhas preferably the well-known make-beforc-break method operation.

' In Fig. 3, I show one arrangement which maybe associated with thc overflow linkcircuits of a cord group -to produce the warning signal at the monitors dosh, before referred to, when a predetermined number of overflow cords are simultaneously employed. 74 is the common signal at. the monitors position. 72 is a connnon relay controlling the said signal and bridged across the conductors '1"? and 78: T5 and 76 being equal resistances interposed in the extensions of the grounded conductors T7 and The resistances r, r, r, and 1", I". 1-. are all equal, the resistances r being associated with manual switches 71 at the monitors desk, by which a desired number of branch circuits may be extended to battery 37.

The relays ll, li ll, are those of three 7%. while each of the relavs ll, dl ,,-ell

assumed to be those of the first three over flow link-circuits, hasits armature -ll controlling the circuit of one of the resistances 9". Assume the signal Tl is to be displayed as soon as the first three overflow cords are simultaneously in use; the three switches 7.1 will accordingly be shifted to connect the three resistances 7' with-conductor 77, and current will flow from battery 37, through the three resistances r, over-conductor 77, passing to ground over the parallel branches extending through resistance 75, and through relay 72* and resistance 76, whet-eon relay 7 2 will attract its armature, Which-Will he effective to prevent the display of signal 74 when the first overflow cord is selectedand relay 44-. operated. At such time, armature l across the points 79 8O will be lessened and part-of its current taken from relay 72, but not enough to allow retraction of its armature 73. When, on selection of two cords,

relays 4.4 and 4A are simultaneously energized, the inclusion of two resistances r will still further reduce the potential across said points; but not until a number of relays -14 have connected resistances 7" to branch 78, equal in number to resistances r of conductor 77, will the potential across the points 79-8O be equal, and relay 7; deprived of current, it being then in substan tially the galvanometer' branch of a balanced \l'heatstone bridge. At'thi-s time, armature T3 will be retracted and lamp 74 displayed. so that the attendant will 'know that the pie-determined number of cords are all in use.

Obviously, if desired, such an arrangement as that shown in Fig. 3 may be provided at every operators position and the lamp arranged to respond to as many simultaneous calls as desired.

If an overflow cord becomes idle. on the consequent deenergization of its relay l4, one resistance T will be disconnected from battery, producing a difference of potential across conductors 77. 78, the energization of relay 72, and the putting out of lamp 74:.

Having thus described my invention, I claim l. A telephone system including a plurality of groups of subscribers lines. a switchboard having a number of operators positions for each group of lines, overflow positions included in said switchboard, a number of main groups of operators? linkcircuits, one for each group of subscribers lines, a plurality of sub-groups included in' each main group of link-circuits, each main group being distributed by sub-groups among the operators positions of the respective line group and to the overflow po- 'sitions, signals for said ll11l (?-l1C11itS, auto matic-testing means whereby any calling line of a group may cause the testing of, first, the circuits of a first sub-group, then the circuits of a second sub'groupvand so on, and finally the circuits of the last subleading to theoverflow positions, to- .find an idle link-circuit, switching means for group connecting the first link-circuit found idle with the calling line and displaying its signal, and manually operated switches for rendering the link-circuits of the sub-groups of a main group extending to positions other than the overflow positions artificially'busy, whereby the calls of the line groups may be turned at will to the overflow positions.

2. A telephone system including a plurality of groups of subscribers lmes,.a switchboard having a number of operators positions for each group of lines, overflow group being distributed by sub-groups among the operators positions-of the re speetive line group and to the overflow positions, signalsfor said link-circuits, automatic testing means whereby any calling line of a group may cause thetesting of, first, the circuits of a first sub-group, then the circuits of a second sub-group, and so on, and finally the circuits of the lastsubgroup leading to the overflow positions, to find an idle link-circuit, switching means for connecting the first link-circuit found idle with the calling line and displaying its sig nal, manually operated switches for rendering the link-circuits of the sub-groups of a main group extending to positions other than the overflow positions artificially busy, whereby the calls of the line groups 'inay'be turned at will to the overflow positions, and operators switching mechanism associated with said link-circuits for extendinglinkcircuits connected to calling lines to any desired line. i

3. A telephone system including a group of subscribers lines, a switchboard having operators positions. an overflow position included in said board, a number of groups of operators" link-circuits and signals there for. each operators position having signals of one group, automatic testing means for said lines for testing, first, the link-circuits of a first group, thereafter the link-circuits.

of a second group, etc., and finally the linkcii'c'uits of the group assigned to the overflow position, when calls are initiated over said lines, to find an idle circuit. switching means for connecting the first link-circuit found idle with a calling line and displaying its signal, and manually operated switches for rendering the .linlccircuits extending to positions other than the overtlow position artificially busy. whereby the calls of the line group may be turned at will to the overflow position.

4. A telephone system i'ncludinga group of subscribers lines, a switchboard having operators positions, 'an overflow position included in said'board, a number of groups of operators link-circuits and signals there? for, each operators position having signals of one group, automatic testing means for said lines for testing, first, "the link-'circuits of a first group, thereafter the link circuits of a second group, etc., and finally the link-circuits of the group assigned to 130 the'overflow position, when calls are inicircuits for each group leading from said l its series of regular positions and to said fixed contacts, aseries of regular operators l special position, switching means for each positions for each group in whicha portion group responsive to eachcall to test first of the link-circuits for that groupterminate l the link-circuits leading to the first regular in an order corresponding to that of said position, then'the second, and so on throughfixed contacts, and a special op'erators position in which the remainder of the link-circuits of the plurality of groups terminate.

12. A telephone system comprising a plurality of series of regular-operators positions, a special. operators position common to said plurality, groups of telephone lines each 'corresponding to one of said series, link-circuits for each said group leading to its series of regular positions and to said special position, switching means for each group responsive to each call to test first the link-circuits leading to the regular positions and then those leading to said special position, circuit connections for automatically impressing a potential on the terminal, of a link-circuit when tested by said means and found idle, to render it busy, and manually controlled switching means for, at will,

-impressing a potential upon, said terminals to render them artificially busy. i I

13. A-telephone system comprising a plurality of series of regular operators positions, :1 special operators position common to said plurality, groups of telephone lines each corresponding to one of saidseries, link-circuits for each said group leading to its series of regular positions and to said special position, switching means for each group responsive to each call to test first the link-circuits leading to the regular positions and then those leading to said special position, and operator controlled devices for connecting said link-circuits to wanted lines.

14. A telephone system comprising a plu rality of series of regular operatorsposi tions, a special operator's, position common to said plurality, groups of telephonelines each corresponding to one of said series, link-circuits for each said group leading to its series of regular positions and to said special position, switching means for each group responsive to each call to test first the link-circuits leading to the first regular position, then the second,"and so on throughout the'regular' positions and finally those leading to said special position, circuit connections for automatically im ressinga potential on the terminal of a 'nk-circuit when tested by said means and found idle, to render it busy, and manually controlled switch-- ing means for, at will, impressing a potential upon said terminals to render them artificially busy. 15. A telephone'system comprising a plurality of series of regular operators"'posiosition common to said p urality, groups 0 telephone lines each ,COII'ESPGYldIDg' to one, ofysaidseries," Hair-circuits for each said group leading to out the regular positions and finally those leading to said special position, and operator controlled devices for connecting said linkcircuits to wanted lines.

'16. A telephone system comprising groups of telephone .lines, a group of selective switches for each group of lines, means responsive to currents over calling lines'to initiate travel of said -switches, traveling test members for said switches, cooperating stationary contacts adapted to be engaged and tested thereby, a series of regular operators positions for each group of lines, an overflow position common to the several groups, link-circuits extending from the said contacts of switches of each group to the corresponding-series of regular operators positions, and link-circuitsextending from the said contacts of switches of all the groups to said. overflow position.

17'. Aitelephone system comprising groups of telephone lines, a group of selective switches for each group of lines, means responsive to currents over calling lines to initiate travel of said switches, traveling test members for said switches, cooperating stationary contacts adapted to be engaged and tested thereby, a series of regular operators positions for each group of lines, an overflow position common to the several, groups, link-circuits extending from the said contacts of switches ofeach group to the corresponding series of regular operators positions, link-circuits extending from the i said contacts of switches of allthe groups to said overflow position, means for automatically placing a busy potential upon the contacts of the first idle link-circuits tested by said traveling members and manually controlled switches for impressing a busy potential upon said contacts.

18. A telephone system comprising. groups of telephone. lines, a group of selectiveswitches for each group of lines,- means responsive to currents over calling lines to' initiate travel of said switches, traveling test =members for said switches, cooperating stationaryv contacts adapted to be engaged and tested thereby,'a series of regular operators positions for each group of lines, an overflow position common tothe several groups, link-circuits extending from the said con-tacts ofswitches'of each group to the corresponding series of regular oiperators positions; link-circuits extending rom the 'sa'idjcontacts'of switches of all the'groups .to said overflow position, and means for connecting link-circuits, tested and. found idle bysaid traveling test members, with calling Qeo,17o

19. A telephone system comprising groups of-telephone lines. a group n of selective switches for each group of lines, means responsive to currents over calling lines to by said traveling test members, with callinglincsrand means for restoring said selective switches-to normal.

20.- A telephone system comprising groups of; telephone lines, a group of selective switches for each group of lines, means responsive to currents over calling lines to initiate travel of said iswitches, traveling test members for said switches-cooperating stationary contacts adapted to be engaged and tested thereby, a series of regular operators positions for each group of lines, an overflow position common to the several groups, link-circuits extending from the said contacts of switches of each group tothe corresponding series of regular operators positions, link-circuits extending from the said contacts of switches of all the groups to said overflow position, signals for said link-circuits displayed responsive to their connection with calling lines, and devices for extending said link-circuits to desired points.

21. A telephone system'comprising a plurality of series of regular'operators positions, a special operators position common to said plurality, groups of telephone lines each corresponding to one of said, series, link-circuits for each said group leading'to its series of regular positions and to said special position, switching means ;for each group res onsive to each call to test first the link-circuits leading to the regular positions and then those leading to said special'position, and means for connecting link-circuits,

tested and found idle by said switching means, with calling lines.

22. A telephone system comprising a plurality of series of regular operators positions, a special operators position common to said plurality, groups of telephone lines each corresponding to one ot's'aid series,

link-circuits for each said group leading to its' series of regular positions and to said specialposition, switching means for each group responsive to each call to test first the link-circuits'leading to the regular positions andthen those leading to said special position, mean: for connecting link-circuits,

special position,

tested and found idle by said switching means,- with calling lines, signals for said link-circuits displayed responsive to their connection with calling l1nes,'and devices for extending said link-circuits to desired points. p

23. A telephone system comprising a plu rality of series of regular operators positions, a special operators position common to said plurality, groups of telephone lines each corresponding to one of said series, linkcircuits tor each said group leading to its se ries of regular positions and to said special position, switching means for each group re.

sponsive to each call totest'tirst thelinkcircuits leading to the first regular position, then thesecond, and so on throughout the regular positions andfinally thoseleading 'to said special position, and means .for connecting linlecircuits, tested and found idle by said switching means, with calling lines. 24:. A telephone system comprisinga plurality of series of regular operators positions, a special opera-tors position commonto said' plurality, groups of telephone lines each corresponding to one ofsaid series,

link-circuits for emihlsaid group leading to its series of i'egulai" positions and to said switch ng means for each group responsive to each call to test first the link-circuits leading to the first regular position, then the second, and so on throughout the regular positions and finally those leading-to said special-position, signals for said li11-l',ici1'ci1its displayed responsive to their connection with calling lines, and devices for extending said link-circuits to desired points.

25.,A telephone system comprising a plurality of series of regulars operators positions, a special operators position common to said plurality. groups of telephone lines each corresponding to one of said series,

link-circuits for each said group leading to its series of regular positions and to said special position, switching means for each group responsive to each call to test iii-st the link-circuits leading to the first regular position, then the second, and so on throughout the regular positions and finally those leading to said special position, and manually controlled switches for placing the link-circuits of said special position in operative contiguity to any desired one of said regular positions. I

26. A telephone system comprising a plurality of series of regular operators positions, a special operators position. common to said plurality, groups of telephone lines each corresponding toone of said series,

link-circuits for each said group leading to link-circuits leading to thefirst regular position, then the second, and so on througl1-- I the calling line and for efl'ecting extensions out the regular positions and finally those thereof to called lines. 10

leading to said special position, manually V In Witness whereof, I hereunto subscribe controlled switches for placing the 1ink-cir-' my name this 13th day of J une, 1907. I cuits of said'special position in operative I LEROY D. KELLOGG.

v contiguity toany desired one of said regular \Vitnesses:

positions, and means for automatically con- I THOMAS H. FERGUSON, necting the first idle link-circuit tested to CAROLYN \VEBER. 

